Systems and methods for adjusting current consumption of control chips to reduce standby power consumption of power converters

ABSTRACT

System and method for regulating a power conversion system. For example, a system controller includes a signal generator and one or more power-consumption components. The signal generator is configured to receive a feedback signal related to an output signal of the power conversion system, a current sensing signal and an input voltage, and to generate a control signal based on at least information associated with the feedback signal, the current sensing signal and the input voltage. The power-consumption components are configured to receive the control signal. The signal generator is further configured to determine whether the feedback signal is smaller than a feedback threshold for a first predetermined period of time, the current sensing signal is smaller than a current sensing threshold for a second predetermined period of time, and the input voltage is smaller than a first threshold for a third predetermined period of time in magnitude.

1. CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.61/432,130, filed Jan. 12, 2011, commonly assigned and incorporated byreference herein for all purposes.

2. BACKGROUND OF THE INVENTION

The present invention is directed to integrated circuits. Moreparticularly, the invention provides a system and method for reducingstandby power consumption. Merely by way of example, the invention hasbeen applied to a power converter. But it would be recognized that theinvention has a much broader range of applicability.

Power converters are widely used for consumer electronics such asportable devices. The power converters can convert electric power fromone form to another form. As an example, the electric power istransformed from alternate current (AC) to direct current (DC), from DCto AC, from AC to AC, or from DC to DC. Additionally, the powerconverters can convert the electric power from one voltage level toanother voltage level.

The power converters include linear converters and switch-modeconverters. The switch-mode converters often have higher efficiency thanthe linear converters. Additionally, the switch-mode converters usuallyuse pulse-width-modulated (PWM) or pulse-frequency-modulated (PFM)mechanisms. Moreover, a PWM switch-mode converter can be either anoffline flyback converter or a forward converter.

The switch-mode converters can consume significant power under standbyconditions, such as with light or zero output loads. But the switch-modeconverters need to meet various international standards concerningenergy saving, such as requirements for Energy Star or Blue Angel.Therefore, the switch-mode converters should have low standby powerconsumption and high power efficiency under light or no load conditions.The no load conditions include, for example, standby, suspend or someother idle conditions. In another example, the standby power consumptionincludes energy losses at various components of the switch-modeconverters such as power switches, transformers, inductors, andsnubbers. These losses often increase with the switching frequency.

To reduce the standby power, the switching frequency is usually loweredfor light or zero output loads. But if the switching frequency becomestoo low and falls within the audio range, unwanted audible noises arise.One way to avoid these audible noises but also reduce standby power isto operate the switch-mode converters in the burst mode. In the burstmode, from time to time, some PWM cycles are skipped and the operationcan become asynchronous depending on the load conditions.

FIG. 1(A) is a simplified diagram showing a conventional off-lineflyback converter. The converter 100 includes a chip 110 for PWMcontrol, a power switch 120, a primary winding 130, a secondary winding132, an auxiliary winding 134, diodes 140, 142, and 144, capacitors 150,152 and 154, resistors 160, 162, 164 and 166, an isolated feedbackcomponent 170, an electromagnetic interference filter 180, and an inputrectifier and filter component 182.

FIG. 1(B) is a simplified diagram showing the conventional chip 110 forPWM control. The chip 110 for PWM control includes a PWM controllercomponent 220, a gate driver 230, an oscillator 240, a protectioncomponent 242, a current and voltage generator 244, aleading-edge-blanking component 246, and an over-current comparator 248.Also, the chip 110 for PWM control includes terminals 112, 114, 116, and118. For example, the PWM controller component 220 includes a PWMcomparator 222 and a logic controller 224. In another example, theprotection component 242 includes one or more components forover-voltage protection, over-temperature protection, over-currentprotection (OCP), and/or over-power protection (OPP). In yet anotherexample, the current and voltage generator 244 is configured to generateone or more voltages and/or one or more currents.

FIG. 1(C) is a simplified diagram showing the conventional isolatedfeedback component 170. The isolated feedback component 170 includesresistors 172, 173 and 174, a capacitor 175, an error amplifier 176, anda photo coupler 178 that includes a photodiode 184 and a phototransistor186.

Referring to FIG. 1(A) and FIG. 1(B), the converter 100 provides anoutput voltage 199 (e.g., V_(o)) and an output current (e.g., I_(o)) toan output load 168, such as an output resistor. In more detail, the PWMcontroller component 220 generates a PWM signal 232, which is receivedby the gate driver 230. In response, the gate driver 230 sends a gatesignal 192 to the power switch 120 through the terminal 112.Accordingly, the power switch 120 adjusts the current 122 flowingthrough the primary winding 130. For example, if the power switch 120 isturned on, the power switch 120 is closed, allowing the current 122 toflow through the primary winding 130. In another example, if the powerswitch is turned off, the power switch 120 is open, thus not allowingthe current 122 to flow through the primary winding 130.

The current 122 is sensed by the resistor 166 and converted into acurrent sensing signal 194 (e.g., V_(cs)) through the terminal 114 andthe leading-edge-blanking component 246. The current sensing signal 194is received by the OCP comparator 248 and compared with an over-currentthreshold signal 195 (e.g., V_(th) _(—) _(oc)). In response, the OCPcomparator 248 sends an over-current control signal 249 to the logiccontroller 224. When the current of the primary winding is greater thana limiting level, the PWM controller component 220 turns off the powerswitch 120 and shuts down the switch-mode power converter 100, thuslimiting the current 122 flowing through the primary winding 130 andprotecting the switch-mode power converter 100.

As shown in FIG. 1(A), FIG. 1(B) and FIG. 1(C), the output voltage 199(e.g., V_(o)) of the secondary winding 132 is sensed by the isolatedfeedback component 170. In response, the isolated feedback component 170sends a feedback signal 198 (e.g., V_(FB)) to the PWM comparator 222through the terminal 118. The PWM comparator 222 also receives thecurrent sensing signal 194 and generates a PWM comparator output signal223. The PWM comparator output signal 223 is received by the logiccontroller 224, which generates the PWM signal 232 based on at leastinformation associated with the PWM comparator output signal 223.

The chip 110 for PWM control is powered by the auxiliary winding 134,the diode 140, the capacitor 150, and the resistor 160 through theterminal 116. When the power switch 120 is turned on, the energy istaken from the input and stored in the primary winding 130. Also, thediode 144 is reverse biased, thus the output load 168 is powered by theenergy stored in the capacitor 154.

When the power switch 120 is turned off, some energy stored in theprimary winding 130 is transferred to the secondary winding 132 that iscoupled to the primary winding 130. Consequently, the diode 144 becomesforward-biased, and the energy is delivered to the capacitor 154 and tothe output load 168. The output voltage 199 (e.g., V_(o)) is alsoreflected back to the primary winding 130, causing an increase of thedrain voltage of the power switch 120 that includes a field effecttransistor (FET).

Additionally, when the power switch 120 is turned off, the energy storedin the primary winding 130 is also transferred to the auxiliary winding134 that is coupled to the primary winding 130. Consequently, the diode140 becomes forward biased, and some energy stored in the primarywinding is delivered to the capacitor 150 and used to provide a chipsupply voltage 196 (e.g., V_(DD)) to the chip 110 through the terminal116. The combination of the auxiliary winding 134, the diode 140, thecapacitor 150, and the resistor 160 is called the self-supply circuit.

FIG. 2 is a simplified conventional diagram showing burst mode operationfor the converter 100. The waveform 202 represents the output voltage199 (e.g., V_(o)) as a function of time, the waveform 204 represents thefeedback signal 198 as a function of time, the waveform 206 representsthe current 122 that flows through the power switch 120 as a function oftime, and the waveform 208 represents a drain-source voltage of thepower switch 120 that includes a FET.

As shown in FIG. 2, T_(on) is the burst-on time, and T_(off) is theburst-off time. During T_(on), the drive signal 192 turns on and off thepower switch 120 at a switching frequency that is above an audiofrequency range, and during T_(off), the power switch 120 remains beingturned off. Also, T_(burst) denotes the burst period that is equal toT_(on) plus T_(off), and T_(on)/T_(burst) represents the burst dutycycle. For example, the burst period depends on the load conditions. Inanother example, the burst duty cycle is reduced in order to lower thestandby power at a given switching frequency. Specifically, the standbypower can be lowered by reducing the burst-on time and/or increasing theburst-off time.

But the burst-on time and the burst-off time can also be constrained bythe current consumption of the chip 110 for PWM control. Referring toFIG. 1(A), the output voltage 199 (e.g., V_(o)) and the chip supplyvoltage 196 (e.g., V_(DD)) are related to each other as follows:

$\begin{matrix}{V_{DD} = {{\frac{V_{o}V_{fb}}{N_{s}} \times N_{a}} - V_{fa}}} & \left( {{Equation}\mspace{14mu} 1} \right)\end{matrix}$

where N_(s) and N_(a) represent the number of turns of the secondarywinding 132 and the number of turns of the auxiliary winding 134respectively. Additionally, V_(fa) and V_(fb) represent the forwardvoltage of the diode 140 and the forward voltage of the diode 144respectively. According to Equation 1, the chip supply voltage 196(e.g., V_(DD)) increases with the increasing output voltage 199 (e.g.,V_(o)), and decreases with the decreasing output voltage 199 (e.g.,V_(o)).

Referring to FIG. 2, during T_(off), the power switch 120 is turned off,causing both the output voltage 199 (e.g., V_(o)) and the chip supplyvoltage 196 (e.g., V_(DD)) to drop. If the chip supply voltage 196(e.g., V_(DD)) becomes smaller than the under-voltage lockout (UVLO)threshold, the chip 110 for PWM control is powered off. Subsequently, astart-up process is initiated. Often, the start-up process can takeseveral seconds, during which, the output voltage 199 (e.g., V_(o))becomes out of regulation and hence falls off.

Therefore, to maintain the output regulation, it is important to keepthe chip supply voltage 196 (e.g., V_(DD)) above the UVLO threshold, andthe burst duty cycle T_(on)/T_(burst) also above a minimum level. Theminimum level of the burse duty cycle is used to maintain theappropriate balance between charging and discharging of the capacitor150 in order to keep the chip supply voltage 196 (e.g., V_(DD)) abovethe UVLO threshold.

FIG. 3 is a simplified conventional diagram showing a relationshipbetween the chip supply voltage 196 (e.g., V_(DD)) and the outputvoltage 199 (e.g., V_(o)) under different load conditions. In Region C,under normal and heavy load conditions, the chip supply voltage 196(e.g., V_(DD)) drifts higher since the charging of the capacitor 150 isstronger than the discharging of the capacitor 150. In contrast, inRegion A, under no load conditions, the chip supply voltage 196 (e.g.,V_(DD)) drifts lower since the charging of the capacitor 150 is weakerthan the discharging of the capacitor 150. Furthermore, the chip supplyvoltage 196 (e.g., V_(DD)) may drop further below the UVLO threshold,and thus enter into Region D. Then, the chip 110 for PWM control ispowered down, hence no switching is performed, and no energy isdelivered to the output load 168 or the capacitor 150.

Afterwards, the capacitor 150 is recharged through the resistor 162. Ifthe chip supply voltage V_(DD) rises above a start-up threshold, thechip 110 for PWM control resumes operations as shown by Region A. But ifthe charging of the capacitor 150 remains weak, the chip supply voltage196 (e.g., V_(DD)) can again fall below the UVLO threshold, as shown byRegion D. Consequently, the converter 100 ends up changing back andforth between Region A and Region D. The output of the converter 100remains out of regulation, and no regulated output voltage can beobtained.

Referring to FIG. 1(A) and FIG. 1(B), the output regulation isaccomplished through the isolated feedback component 170. The isolatedfeedback component 170 receives the output voltage 199 (e.g., V_(o)) andsends the feedback signal 198 to the chip 110 through the terminal 118.The feedback signal 198 represents the output voltage 199 (e.g., V_(o)).Hence the drive signal 192 with PWM modulation is controlled by at leastthe feedback signal 198 in order to regulate the output voltage 199(e.g., V_(o)) to the desired voltage level.

In contrast, the chip supply voltage 196 (e.g., V_(DD)) is notregulated. The variation in the chip supply voltage 196 is not correctedthrough any feedback loop. To keep the chip supply voltage 196 above theUVLO threshold, a dummy load often is added to the output of theconverter 100 in order to maintain the output regulation even under noload conditions. But the dummy load consumes a constant power and hencedegrades the power efficiency of the converter 100, especially underlight or no load conditions.

Hence it is highly desirable to improve the techniques for reducingstandby power consumption.

3. BRIEF SUMMARY OF THE INVENTION

The present invention is directed to integrated circuits. Moreparticularly, the invention provides a system and method for reducingstandby power consumption. Merely by way of example, the invention hasbeen applied to a power converter. But it would be recognized that theinvention has a much broader range of applicability.

According to one embodiment, a system controller for regulating a powerconversion system includes a signal generator configured to receive afeedback signal related to an output signal of a power conversionsystem, a current sensing signal and an input voltage, and to generate acontrol signal based on at least information associated with thefeedback signal, the current sensing signal and the input voltage, thecurrent sensing signal representing one or more peak magnitudes relatedto a primary current flowing through a primary winding of the powerconversion system, and one or more power-consumption componentsconfigured to receive the control signal. The one or morepower-consumption components are further configured to reduce powerconsumption if the control signal indicates the feedback signal issmaller than a feedback threshold for a first predetermined period oftime, the current sensing signal is smaller than a current sensingthreshold for a second predetermined period of time, and the inputvoltage is smaller than a first threshold for a third predeterminedperiod of time in magnitude. Each of the first predetermined period oftime, the second predetermined period of time, and the thirdpredetermined period of time is equal to or larger than zero inmagnitude.

According to another embodiment, a system controller for regulating apower conversion system includes a signal generator configured toreceive a feedback signal related to an output signal of a powerconversion system, a current sensing signal and an input voltage, and togenerate a control signal based on at least information associated withthe feedback signal, the current sensing signal and the input voltage,the current sensing signal representing one or more peak magnitudesrelated to a primary current flowing through a primary winding of thepower conversion system, and one or more power-consumption componentsconfigured to receive the control signal. The one or morepower-consumption components are further configured to reduce powerconsumption if the control signal indicates the feedback signal islarger than a feedback threshold for a first predetermined period oftime, the current sensing signal is smaller than a current sensingthreshold for a second predetermined period of time, and the inputvoltage is smaller than a first threshold for a third predeterminedperiod of time in magnitude. Each of the first predetermined period oftime, the second predetermined period of time, and the thirdpredetermined period of time is equal to or larger than zero inmagnitude.

According to yet another embodiment, a system controller for regulatinga power conversion system includes a first resistor including a firstresistor terminal and a second resistor terminal, the first resistorterminal being biased to a first predetermined voltage, a secondresistor including a third resistor terminal and a fourth resistorterminal, the third resistor terminal being connected to the secondresistor terminal, the fourth resistor terminal configured to receive afeedback signal related to an output signal of a power conversionsystem, a transistor including a first transistor terminal, a secondtransistor terminal, and a third transistor terminal, the firsttransistor terminal being connected to the second resistor terminal andthe third resistor terminal, the second transistor terminal beingconfigured to receive a second predetermined voltage, the thirdtransistor terminal being configured to receive the feedback signal, amodulation component configured to receive the feedback signal andgenerate a modulation signal, and a gate driver configured to receivethe modulation signal and output a drive signal to a switch foradjusting a primary current flowing through a primary winding of thepower conversion system.

According to yet another embodiment, a method for regulating a powerconversion system includes receiving a feedback signal related to anoutput signal of a power conversion system, a current sensing signal andan input voltage, the current sensing signal representing one or morepeak magnitudes related to a primary current flowing through a primarywinding of the power conversion system, processing informationassociated with the feedback signal, the current sensing signal and theinput voltage, and generating a control signal based on at leastinformation associated with the feedback signal, the current sensingsignal and the input voltage. The method further includes receiving thecontrol signal, processing information associated with the controlsignal, and, if the control signal indicates the feedback signal issmaller than a feedback threshold for a first predetermined period oftime, the current sensing signal is smaller than a current sensingthreshold for a second predetermined period of time, and the inputvoltage is smaller than a first threshold for a third predeterminedperiod of time in magnitude, reducing power consumption of one or morepower consumption components. Each of the first predetermined period oftime, the second predetermined period of time, and the thirdpredetermined period of time is equal to or larger than zero inmagnitude.

Many benefits are achieved by way of the present invention overconventional techniques. Certain embodiments of the present inventionprovide a method to reduce standby power consumption in pulse widthmodulation (PWM) controlled switch mode power converters including butnot limited to an offline fly-back converter, and a forward converter.Some embodiments of the present invention provide a method tointelligently and dynamically manage internal current consumption of aPWM controller IC to reduce the overall standby power consumption of apower converter.

Certain embodiments of the present invention provide a method to reduceinternal current consumption under light load or no load conditions toreduce the overall standby power consumption of a switching powerconverter. For example, the current consumption of a PWM controller isdynamically managed in response to different load conditions. In anotherexample, the current consumption of the PWM controller is reduced underlight load or no load conditions by powering down some functional blockswhich are not necessary under those conditions. In yet another example,meanwhile, the current consumption of other function blocks is reducedwithout degrading dynamic performance of the switching power converterunder light load or no load conditions. Charges held on a power-supplyholding capacitor supply the PWM controller for a long time withoutswitching thus results in low standby power consumption in someembodiments of the present invention.

Certain embodiments of the present invention provide a method to managecurrent consumption of a PWM controller that works in several powermodes, such as a normal operation mode, a power saving mode, and a powerdissipation mode. For example, in a power saving mode, the currentconsumption of the PWM controller is reduced in order to reduce standbypower consumption. In another example, in a power dissipation mode, thePWM controller consumes more power than in a normal operation mode toprevent a power supply voltage of the PWM controller from drifting highto protect the PWM controller.

Depending upon embodiment, one or more of these benefits may beachieved. These benefits and various additional objects, features andadvantages of the present invention can be fully appreciated withreference to the detailed description and accompanying drawings thatfollow.

4. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1(A) is a simplified diagram showing a conventional off-lineflyback converter.

FIG. 1(B) is a simplified diagram showing the conventional chip of FIG.1(A) for PWM control.

FIG. 1(C) is a simplified diagram showing the conventional isolatedfeedback component of FIG. 1(A).

FIG. 2 is a simplified conventional diagram showing burst mode operationfor the converter of FIG. 1(A).

FIG. 3 is a simplified conventional diagram showing a relationshipbetween the chip supply voltage and the output voltage as shown in FIG.1(A) and FIG. 1(B) under different load conditions.

FIG. 4 shows a simplified diagram showing standby power consumption anddummy load as functions of current consumption of the chip of FIG. 1(A)for PWM control according to one embodiment.

FIG. 5 is a simplified diagram showing a power converter with dynamicmanagement of chip current consumption for PWM control according to anembodiment of the present invention.

FIG. 6 is a simplified diagram showing dynamic management of chipcurrent consumption by the power converter of FIG. 5 according to anembodiment of the present invention.

FIG. 7 is a simplified diagram showing the management monitoringcomponent and the management control component of the power converter ofFIG. 5 according to an embodiment of the present invention.

FIG. 8 is a simplified diagram showing a power converter with dynamicmanagement of chip current consumption for PWM control according toanother embodiment of the present invention.

FIG. 9 is a simplified diagram showing a power converter with dynamicmanagement of chip current consumption for PWM control according to yetanother embodiment of the present invention.

FIG. 10 is a simplified diagram showing a power converter with dynamicmanagement of chip current consumption for PWM control according to yetanother embodiment of the present invention.

FIG. 11 is a simplified diagram showing a power converter with dynamicmanagement of chip current consumption for PWM control according to yetanother embodiment of the present invention.

5. DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to integrated circuits. Moreparticularly, the invention provides a system and method for reducingstandby power consumption. Merely by way of example, the invention hasbeen applied to a power converter. But it would be recognized that theinvention has a much broader range of applicability.

As discussed above, the dummy load is used to prevent the chip supplyvoltage 196 (e.g., V_(DD)) from dropping below the UVLO threshold if thecharging of the capacitor 150 is insufficient to balance the currentconsumption of the chip 110. When the power switch 120 is turned off,the drop rate of the chip supply voltage 196 (e.g., V_(DD)) depends onthe current consumption of the chip 110.

If the current consumption of the chip 110 becomes larger, the chipsupply voltage V_(DD) drops faster. Consequently, a larger dummy load isneeded in order to maintain the balance between charging and dischargingof the capacitor 150 and prevent the chip supply voltage 196 (e.g.,V_(DD)) from falling below the UVLO threshold. But the larger dummy loadresults in higher standby power.

FIG. 4 shows a simplified diagram showing standby power consumption anddummy load as functions of current consumption of the chip 110 for PWMcontrol according to one embodiment. A curve 410 represents the standbypower consumption as a function of current consumption of the chip 110,and a curve 420 represents the dummy load as a function of currentconsumption of the chip 110. As shown in FIG. 4, the dummy load and thestandby power consumption increase with the current consumption of thechip 110. Therefore, reducing the current consumption of the chip 110 isimportant for lowering standby power consumption according to certainembodiments.

FIG. 5 is a simplified diagram showing a power converter with dynamicmanagement of chip current consumption for PWM control according to anembodiment of the present invention. This diagram is merely an example,which should not unduly limit the scope of the claims. One of ordinaryskill in the art would recognize many variations, alternatives, andmodifications.

The converter 500 includes a chip 510 for PWM control, the power switch120, the primary winding 130, the secondary winding 132, the auxiliarywinding 134, the diodes 140 and 144, the capacitors 150, 152 and 154,the resistors 164 and 166, and an isolated feedback component 570. Thechip 510 for PWM control includes a PWM controller component 520, a gatedriver 530, an oscillator 540, a protection component 542, a current andvoltage generator 544, a leading-edge-blanking component 546, anover-current comparator 548, a management monitoring component 550, amanagement control component 552, and an adjustable resistor 554. Also,the chip 510 for PWM control includes terminals 512, 514, 516, and 518.

In one embodiment, the PWM controller component 520, the gate driver530, the leading-edge-blanking component 546, and the over-currentcomparator 548 are the same as the PWM controller component 220, thegate driver 230, the leading-edge-blanking component 246, and theover-current comparator 248, respectively.

For example, the PWM controller component 520 includes a PWM comparator522 and a logic controller 524. In another example, the isolatedfeedback component 570 includes resistors 572, 573 and 574, a capacitor575, an error amplifier 576, and a photo coupler 578. In yet anotherexample, the converter 500 provides an output voltage 599 (e.g., V_(o))and an output current (e.g., I_(o)) to the output load 168, such as theoutput resistor.

As shown in FIG. 5, the PWM controller component 520 generates a PWMsignal 532, which is received by the gate driver 530 according to oneembodiment. For example, the gate driver 530, in response, sends a gatesignal 592 to the power switch 120 through the terminal 512 (e.g.,terminal Gate). In another example, in response, the power switch 120adjusts a current 593 flowing through the primary winding 130. In yetanother example, the current 593 is sensed by the resistor 166 andconverted into a current sensing signal 594 (e.g., V_(cs)) through theterminal 514 (e.g., terminal CS) and the leading-edge-blanking component546. In yet another example, the current sensing signal 594 is receivedby the OCP comparator 548 and compared with an over-current thresholdsignal 595 (e.g., V_(th) _(—) _(oc)). In response, the OCP comparator548 sends an over-current control signal 549 to the logic controller 524according to certain embodiments.

As shown in FIG. 5, the chip 510 for PWM control is powered by at leastthe auxiliary winding 134 and the capacitor 150 through the terminal 516(e.g., terminal V_(DD)) according to one embodiment. For example, thecapacitor 150 is used to provide a chip supply voltage 596 (e.g.,V_(DD)) to the chip 510 through the terminal 516. In another example,the output voltage 599 (e.g., V_(o)) of the secondary winding 132 issensed by the isolated feedback component 570. In yet another example,the isolated feedback component 570 generates a feedback signal 598(e.g., V_(FB)) that is received by the adjustable resistor 554. In yetanother example, both the PWM comparator 522 and the managementmonitoring component 550 also receive the feedback signal 598 throughthe terminal 518 (e.g., FB). In yet another example, the PWM comparator522 also receives the current sensing signal 594 and generates a PWMcomparator output signal 523. The PWM comparator output signal 523 isreceived by the logic controller 524, which generates the PWM signal 532based on at least information associated with the PWM comparator outputsignal 523 according to one embodiment. For example, a feedbackimpedance associated with the terminal 518 (e.g., FB) changes withoutput load conditions.

FIG. 6 is a simplified diagram showing dynamic management of chipcurrent consumption by the power converter 500 according to anembodiment of the present invention. This diagram is merely an example,which should not unduly limit the scope of the claims. One of ordinaryskill in the art would recognize many variations, alternatives, andmodifications. For example, the dynamic management of chip currentconsumption is implemented by monitoring the feedback signal 598 (e.g.,V_(FB)), the current sensing signal 594 (e.g., V_(cs)), and the chipsupply voltage 596 (e.g., V_(DD)). In another example, current sensingsignal 594 (e.g., V_(cs)) is used to determine the peak magnitude of thecurrent 593.

According to one embodiment, if the feedback signal 598 (e.g., V_(FB))is determined to be larger than a feedback threshold (e.g., V_(FB) _(—)_(th)) in magnitude, and the current sensing signal 594 (e.g., V_(cs)that represents the peak magnitude of the current 593) is determined tobe larger than a current sensing threshold (e.g., V_(cs) _(—) _(th)) inmagnitude, the converter 500 operates in Region III. For example, inRegion III, a normal or heavy load is recognized, and in response, thePWM controller component 520 operates in a normal mode with a relativelyhigh switching frequency. In another example, in Region III, the drivesignal 592 turns on and off the power switch 120 at the switchingfrequency. In yet another example, relatively high level of energy isdelivered to the load by the converter 500 in Region III. In yet anotherexample, the energy delivered from the primary winding 130 through theauxiliary winding 134 is relatively high and sufficient to supply thechip 510 for PWM control. All the functions, such as all the protectionfunctions, are active under normal and heavy load conditions in RegionIII according to certain embodiments.

According to another embodiment, if the feedback signal 598 (e.g.,V_(FB)) is determined to be smaller than the feedback threshold (e.g.,V_(FB) _(—) _(th)) in magnitude for a first predetermined period oftime, and the current sensing signal 594 (e.g., V_(cs)) is determined tobe smaller than the current sensing threshold (e.g., V_(cs) _(—) _(th))in magnitude for a second predetermined period of time, the converter500 operates in Region I, Region II, or Region VI. For example, if thechip supply voltage 596 (e.g., V_(DD)) is determined to be lower thanthe supply lower threshold (e.g., V_(DD) _(—) _(th) _(—) _(l)) inmagnitude for a third predetermined period of time, the converter 500operates in Region II. In another example, if the chip supply voltage596 (e.g., V_(DD)) is determined to be higher than the supply upperthreshold (e.g., V_(DD) _(—) _(th) _(—) _(h)) in magnitude for a fourthpredetermined period of time, the converter 500 operates in Region I. Inyet another example, if the chip supply voltage 596 (e.g., V_(DD))neither remains lower than the supply lower threshold (e.g., V_(DD) _(—)_(th) _(—) _(l)) in magnitude for the third predetermined period of timenor remains higher than the supply upper threshold (e.g., V_(DD) _(—)_(th) _(—) _(h)) in magnitude for the fourth predetermined period oftime, the converter 500 operates in Region IV. In yet another example,each of the first predetermined period of time, the second predeterminedperiod of time, the third predetermined period of time, and the fourthpredetermined period of time is equal to or larger than zero inmagnitude.

According to yet another embodiment, if the first predetermined periodof time is equal to zero, then the converter 500 operates in Region I,Region II, or Region IV if the feedback signal 598 (e.g., V_(FB)) isdetermined to be smaller than the feedback threshold (e.g., V_(FB) _(—)_(th)) in magnitude, and the current sensing signal 594 (e.g., V_(cs))is determined to be smaller than the current sensing threshold (e.g.,V_(cs) _(—) _(th)) in magnitude for the second predetermined period oftime. For example, if the second predetermined period of time is equalto zero, then the converter 500 operates in Region I, Region II, orRegion IV if the feedback signal 598 (e.g., V_(FB)) is determined to besmaller than the feedback threshold (e.g., V_(FB) _(—) _(th)) inmagnitude for the first predetermined period of time, and the currentsensing signal 594 (e.g., V_(cs)) is determined to be smaller than thecurrent sensing threshold (e.g., V_(cs) _(—) _(th)) in magnitude. Inanother example, if both the first predetermined period of time and thesecond predetermined period of time are equal to zero, then theconverter 500 operates in Region I, Region II, or Region IV if thefeedback signal 598 (e.g., V_(FB)) is determined to be smaller than thefeedback threshold (e.g., V_(FB) _(—) _(th)) in magnitude, and thecurrent sensing signal 594 (e.g., V_(cs)) is determined to be smallerthan the current sensing threshold (e.g., V_(cs) _(—) _(th)) inmagnitude.

According to yet another embodiment, if the third predetermined periodof time is equal to zero, the converter 500 operates in Region II if thefeedback signal 598 (e.g., V_(FB)) is determined to be smaller than thefeedback threshold (e.g., V_(FB) _(—) _(th)) in magnitude for the firstpredetermined period of time, the current sensing signal 594 (e.g.,V_(cs)) is determined to be smaller than the current sensing threshold(e.g., V_(cs) _(—) _(th)) in magnitude for the second predeterminedperiod of time, and the chip supply voltage 596 (e.g., V_(DD)) isdetermined to be lower than the supply lower threshold (e.g., V_(DD)_(—) _(th) _(—) _(l)) in magnitude. For example, if the fourthpredetermined period of time is equal to zero, the converter 500operates in Region I if the feedback signal 598 (e.g., V_(FB)) isdetermined to be smaller than the feedback threshold (e.g., V_(FB) _(—)_(th)) in magnitude for the first predetermined period of time, thecurrent sensing signal 594 (e.g., V_(cs)) is determined to be smallerthan the current sensing threshold (e.g., V_(cs) _(—) _(th)) inmagnitude for the second predetermined period of time, and the chipsupply voltage 596 (e.g., V_(DD)) is determined to be higher than thesupply upper threshold (e.g., V_(DD) _(—) _(th) _(—) _(h)) in magnitude.In yet another example, if both the third predetermined period of timeand the fourth predetermined period of time are equal to zero, theconverter 500 operates in Region IV if the feedback signal 598 (e.g.,V_(FB)) is determined to be smaller than the feedback threshold (e.g.,V_(FB) _(—) _(th)) in magnitude for the first predetermined period oftime, the current sensing signal 594 (e.g., V_(cs)) is determined to besmaller than the current sensing threshold (e.g., V_(cs) _(—) _(th)) inmagnitude for the second predetermined period of time, and the chipsupply voltage 596 (e.g., V_(DD)) neither remains lower than the supplylower threshold (e.g., V_(DD) _(—) _(th) _(—) _(l)) in magnitude norremains higher than the supply upper threshold (e.g., V_(DD) _(—) _(th)_(—) _(h)) in magnitude.

According to yet another embodiment, the first predetermined period oftime, the second predetermined period of time, the third predeterminedperiod of time, and the fourth predetermined period of time are allequal to zero. For example, if the feedback signal 598 (e.g., V_(FB)) isdetermined to be smaller than the feedback threshold (e.g., V_(FB) _(—)_(th)) in magnitude, and the current sensing signal 594 (e.g., V_(cs)that represents the peak magnitude of the current 593) is determined tobe smaller than the current sensing threshold (e.g., V_(cs) _(—) _(th))in magnitude, the converter 500 operates in Region I, Region II, orRegion VI. For example, if the chip supply voltage 596 (e.g., V_(DD)) isdetermined to be higher than the supply upper threshold (e.g., V_(DD)_(—) _(th) _(—) _(h)), the converter 500 operates in Region I. Inanother example, if the chip supply voltage 596 (e.g., V_(DD)) isdetermined to be lower than the supply lower threshold (e.g., V_(DD)_(—) _(th) _(—) _(l)), the converter 500 operates in Region II. In yetanother example, if the chip supply voltage 596 (e.g., V_(DD)) isdetermined to be lower than the supply upper threshold (e.g., V_(DD)_(—) _(th) _(—) _(l)) and higher than the supply lower threshold (e.g.,V_(DD) _(—) _(th) _(—) _(l)), the converter 500 operates in Region IV.

In one embodiment, a light or no load condition is recognized withrespect to Regions I, II, and IV. For example, the switching frequencyis set to a relatively low level, and the PWM controller component 520operates in the burst mode. In another example, relatively low energy isdelivered from the primary winding 130 through the auxiliary winding 134to the capacitor 150 in Regions I, II, and IV.

In another embodiment, if the chip supply voltage 596 (e.g., V_(DD)) isdetermined to be lower than the supply lower threshold (e.g., V_(DD)_(—) _(th) _(—) _(l)) in magnitude for the third predetermined period oftime, the chip 510 for PWM control enters a power saving mode as shownin Region II. For example, under the power saving mode, some functionsof the chip 510 that are unnecessary are powered down in order to reducethe current consumption of the chip 510 for PWM control, thus keepingthe chip supply voltage 596 (e.g., V_(DD)) from quickly falling belowthe under-voltage lockout (UVLO) threshold. In another example, if thecurrent consumption of the chip 510 is reduced in Region II, theconverter 500 can operate with lower burst duty cycle under burst modeoperation and with lower standby power.

In yet another embodiment, if the chip supply voltage 596 (e.g., V_(DD))is determined to be higher than the supply upper threshold (e.g., V_(DD)_(—) _(th) _(—) _(h)) in magnitude for the fourth predetermined periodof time, the chip 510 for PWM control enters a power dissipation mode asshown in Region I. For example, the chip supply voltage 596 (e.g.,V_(DD)) drifts too high due to low current consumption of the chip 510.In another example, under the power dissipation mode, extra power isdissipated in order to prevent the chip supply voltage 596 (e.g.,V_(DD)) from damaging the chip 510 for PWM control.

In yet another embodiment, if the chip supply voltage 596 (e.g., V_(DD))neither remains lower than the supply lower threshold (e.g., V_(DD) _(—)_(th) _(—) _(l)) in magnitude for the third predetermined period of timenor remains higher than the supply upper threshold (e.g., V_(DD) _(—)_(th) _(—) _(h)) in magnitude for the fourth predetermined period oftime, the chip 510 for PWM control enters the normal mode as shown inRegion IV. For example, the PWM controller component 520 operates in thenormal mode with a relatively low switching frequency. In anotherexample, the drive signal 592 turns on and off the power switch 120 atthe switching frequency. In yet another example, all the functions ofthe chip 510, such as all the protection functions, are active in RegionIV.

Returning to FIG. 5, the feedback signal 598 (e.g., V_(FB)), the currentsensing signal 594 (e.g., V_(cs)), and the chip supply voltage 596(e.g., V_(DD)) are received by the management monitoring component 550according to certain embodiments. For example, the management monitoringcomponent 550 compares the feedback signal 598 (e.g., V_(FB)) with thefeedback threshold (e.g., V_(FB) _(—) _(th)), the current sensing signal594 (e.g., V_(cs) that represents the peak magnitude of the current 593)with the current sensing threshold (e.g., V_(cs) _(—) _(th)), and thechip supply voltage 596 (e.g., V_(DD)) with both the supply upperthreshold (e.g., V_(DD) _(—) _(th) _(—) _(h)) and the supply lowerthreshold (e.g., V_(DD) _(—) _(th) _(—) _(l)). In another example, themanagement monitoring component 550 generates a monitoring signal 551,which is received by the management control component 552. In yetanother example, the management control component 552 in response sendsa management control signal 553 to the gate driver 530, the adjustableresistor 554, the oscillator 540, the protection component 542, and thecurrent and voltage generator 544.

According to another embodiment, if the management monitoring component550 determines that the feedback signal 598 (e.g., V_(FB)) is smallerthan the feedback threshold (e.g., V_(FB) _(—) _(th)) in magnitude forthe first predetermined period of time, the current sensing signal 594(e.g., V_(cs) that represents the peak magnitude of the current 593) issmaller than the current sensing threshold (e.g., V_(cs) _(—) _(th)) inmagnitude for the second predetermined period of time, and the chipsupply voltage 596 (e.g., V_(DD)) is lower than the supply lowerthreshold (e.g., V_(DD) _(—) _(th) _(—) _(l)) in magnitude for the thirdpredetermined period of time, the management monitoring component 550sends the monitoring signal 551 to the management control component 552and in response the converter 500 operates in Region II (e.g., as shownin FIG. 6). For example, the management control component 552 generatesthe management control signal 553, which is received by the gate driver530, the adjustable resistor 554, the oscillator 540, the protectioncomponent 542, and the current and voltage generator 544 to adjust thepower consumption or power down some functional blocks (e.g., as shownin FIG. 7). In another example, in Region II, the functional block forover-voltage protection, the functional block for over-temperatureprotection, the functional block for over-current protection (OCP),and/or the functional block for over-power protection (OPP) are powereddown.

According to yet another embodiment, in Region II, the adjustableresistor 554 become larger than in Region III and in Region IV. Forexample, the adjustable resistor 554 is biased between a referencevoltage 555 (e.g., V_(ref)) and the feedback signal 598 (e.g., V_(FB)),so increasing the resistance value of the resistor 554 can reduce thecurrent consumption of the chip 510 and also reduce the currentassociated with the photo coupler 578 for loop regulation. In anotherexample, the change in resistance of the resistor 554 does not affectthe loop stability even under no load condition.

According to yet another embodiment, if the management monitoringcomponent 550 determines that the feedback signal 598 (e.g., V_(FB)) issmaller than the feedback threshold (e.g., V_(FB) _(—) _(th)) inmagnitude for the first predetermined period of time, the currentsensing signal 594 (e.g., V_(cs) that represents the peak magnitude ofthe current 593) is smaller than the current sensing threshold (e.g.,V_(cs) _(—) _(th)) in magnitude for the second predetermined period oftime, and the chip supply voltage 596 (e.g., V_(DD)) is higher than thesupply upper threshold (e.g., V_(DD) _(—) _(th) _(—) _(h)) in magnitudefor the fourth predetermined period of time, the management monitoringcomponent 550 sends the monitoring signal 551 to the management controlcomponent 552 and in response the converter 500 operates in Region I(e.g., as shown in FIG. 6). For example, the management controlcomponent 552 generates the management control signal 553, which isreceived by the gate driver 530, the adjustable resistor 554, theoscillator 540, the protection component 542, and the current andvoltage generator 544. In another example, in Region I, the currentconsumption of the chip 510 is larger than in Region II. In yet anotherexample, an extra current path is provided to discharge the capacitor150 in order to prevent the chip supply voltage 596 (e.g., V_(DD)) fromdrifting even higher. In yet another example, the converter 500 operatesin Region II when the management control signal 553 is at a logic lowlevel (or at a logic high level), and the converter 500 operates inRegion IV when the management control signal 553 is at the logic highlevel (or at the logic low level). In yet another example, themanagement control signal 553 includes two or more logic controlsignals, and the converter 500 operates in different Regions (e.g., asshown in FIG. 6) based on the states of the two or more logic controlsignals.

FIG. 7 is a simplified diagram showing the management monitoringcomponent 550 and the management control component 552 of the powerconverter 500 according to an embodiment of the present invention. Thisdiagram is merely an example, which should not unduly limit the scope ofthe claims. One of ordinary skill in the art would recognize manyvariations, alternatives, and modifications. The management monitoringcomponent 550 includes comparators 810, 820, 830 and 840, timercomponents 812, 822, 832 and 842, and a pattern recognition logiccomponent 850. For example, the timer component 832 includes a timingfunctional block and a low-pass filtering functional block.

As shown in FIG. 7, the comparators 810 and 820 each receive the chipsupply voltage 596 (e.g., V_(DD)), the comparator 830 receives thecurrent sensing signal 594 (e.g., V_(cs)), and the comparator 840receives the feedback signal 598 (e.g., V_(FB)), according to oneembodiment. For example, the comparator 810 compares the chip supplyvoltage 596 with the supply upper threshold (e.g., V_(DD) _(—) _(th)_(—) _(h)) and generates a comparison signal 811. In another example,the comparator 820 compares the chip supply voltage 596 with the supplylower threshold (e.g., V_(DD) _(—) _(th) _(—) _(l)) and generates acomparison signal 821. In yet another example, the comparator 830compares the current sensing signal 594 (e.g., V_(cs) that representsthe peak magnitude of the current 593) with the current sensingthreshold (e.g., V_(cs) _(—) _(th)) and generates a comparison signal831. In yet another example, the comparator 840 compares the feedbacksignal 598 (e.g., V_(FB)) with the feedback threshold (e.g., V_(FB) _(—)_(th)) and generates a comparison signal 841.

According to another embodiment, the comparator signals 811, 821, 831,and 841 are received by the timer components 812, 822, 832 and 842,respectively. For example, the timer component 812 outputs a signal 813,which indicates whether the chip supply voltage 596 remains larger thanthe supply upper threshold (e.g., V_(DD) _(—) _(th) _(—) _(h)) for apredetermined period of time (e.g., T₁). In another example, the timercomponent 822 outputs a signal 823, which indicates whether the chipsupply voltage 596 remains smaller than the supply lower threshold(e.g., V_(DD) _(—) _(th) _(—) _(l)) for a predetermined period of time(e.g., T₂). In yet another example, the current sensing signal 594 is apulse signal, and the timer component 832 performs a low-pass filteringprocess performs on the comparator signal 831. In yet another example,the timer component 832 outputs a signal 833, which indicates whetherthe current sensing signal 594 (e.g., V_(cs) that represents the peakmagnitude of the current 122) remains smaller than the current sensingthreshold (e.g., V_(cs) _(—) _(th)) for a predetermined period of time(e.g., T₃). In yet another example, the timer component 842 outputs asignal 843, which indicates whether the feedback signal 598 (e.g.,V_(FB)) remains smaller than the feedback threshold (e.g., V_(FB) _(—)_(th)) for a predetermined period of time (e.g., T₄). In yet anotherexample, each of T₁, T₂, T₃ and T₄ is larger than zero in magnitude.

In one embodiment, the timer component 812 is omitted, and the signal813 is the same as the signal 811. In another embodiment, the timercomponent 822 is omitted, and the signal 823 is the same as the signal813. In yet another embodiment, the timing functional block in the timercomponent 832 is omitted. In yet another embodiment, the timer component842 is omitted, and the signal 843 is the same as the signal 841.

According to yet another embodiment, the pattern recognition logiccomponent 850 receives the signals 813, 823, 833, and 843, and inresponse generates the monitoring signal 551, which indicates whetherthe feedback signal 598 (e.g., V_(FB)), the current sensing signal 594(e.g., V_(cs)), and the chip supply voltage 596 (e.g., V_(DD)) satisfythe conditions for Region I, Region II, Region III, or Region IV, asshown in FIG. 6.

For example, if the feedback signal 598 (e.g., V_(FB)) remains smallerthan the feedback threshold (e.g., V_(FB) _(—) _(th)) for thepredetermined period of time (e.g., T₄), the current sensing signal 594(e.g., V_(cs) that represents the peak magnitude of the current 122)remains smaller than the current sensing threshold (e.g., V_(cs) _(—)_(th)) for the predetermined period of time (e.g., T₃), and the chipsupply voltage 596 (e.g., V_(DD)) remains larger than the supply upperthreshold (e.g., V_(DD) _(—) _(th) _(—) _(h)) for the predeterminedperiod of time (e.g., T₁), the conditions for Region I are satisfied. Inanother example, if the feedback signal 598 (e.g., V_(FB)) remainssmaller than the feedback threshold (e.g., V_(FB) _(—) _(th)) for thepredetermined period of time (e.g., T₄), the current sensing signal 594(e.g., V_(cs) that represents the peak magnitude of the current 122)remains smaller than the current sensing threshold (e.g., V_(cs) _(—)_(th)) for the predetermined period of time (e.g., T₃), and the chipsupply voltage 596 (e.g., V_(DD)) remains smaller than the supply lowerthreshold (e.g., V_(DD) _(—) _(th) _(—) _(l)) for the predeterminedperiod of time (e.g., T₂), the conditions for Region II are satisfied.

In yet another example, if the feedback signal 598 (e.g., V_(FB))remains smaller than the feedback threshold (e.g., V_(FB) _(—) _(th))for the predetermined period of time (e.g., T₄), and the current sensingsignal 594 (e.g., V_(cs) that represents the peak magnitude of thecurrent 122) remains smaller than the current sensing threshold (e.g.,V_(cs) _(—) _(th)) for the predetermined period of time (e.g., T₃), butthe chip supply voltage 596 (e.g., V_(DD)) does not remain larger thanthe supply upper threshold (e.g., V_(DD) _(—) _(th) _(—) _(h)) for thepredetermined period of time (e.g., T₁) and the chip supply voltage 596(e.g., V_(DD)) does not remain smaller than the supply lower threshold(e.g., V_(DD) _(—) _(th) _(—) _(l)) for the predetermined period of time(e.g., T₂), the conditions for Region IV are satisfied. In yet anotherexample, if the feedback signal 598 (e.g., V_(FB)) does not remainsmaller than the feedback threshold (e.g., V_(FB) _(—) _(th)) for thepredetermined period of time (e.g., T₄), and the current sensing signal594 (e.g., V_(cs) that represents the peak magnitude of the current 122)does not remain smaller than the current sensing threshold (e.g., V_(cs)_(—) _(th)) for the predetermined period of time (e.g., T₃), theconditions for Region III are satisfied.

As shown in FIG. 7, the management control component 552 receives themonitoring signal 551, and in response generates the management controlsignal 553. For example, the management control signal 553 is receivedby a functional block 860 for over-temperature protection (OTP), afunctional block 862 for over-power protection (OPP), a functional block864 for over-voltage protection (OVP), and a functional block 866 forover-current protection (OCP). In another example, the managementcontrol signal 553 is also received by a functional block 870 for theunder-voltage lockout (UVLO) threshold, and a functional block 872 forreference voltage generation. In yet another example, the managementcontrol signal 553 is also received by a functional block 874 for erroramplification, the PWM controller 520, the gate driver 530, and theoscillator 540. In yet another example, the management control signal553 is also received by a functional block 880 for current bias, afunctional block 882 for voltage bias, and a functional block 845 forcurrent and voltage generation. In yet another example, the functionalblock 860 for over-temperature protection, the functional block 862 forover-power protection, the functional block 864 for over-voltageprotection, the functional block 866 for over-current protection, andthe functional block 870 for the under-voltage lockout threshold areincluded in the protection component 542. In yet another example, thefunctional block 872 for reference voltage generation, the functionalblock 880 for current bias, the functional block 882 for voltage bias,and the functional block 845 for current and voltage generation areincluded in the current and voltage generator 544. In yet anotherexample, the functional block 874 for error amplification is included inthe adjustable resistor 554.

In one embodiment, if the monitoring signal 551 indicates the conditionsfor Region II are satisfied, the current consumption for the functionalblock 860, the functional block 862, the functional block 864, thefunctional block 866, the functional block 870, the functional block872, an error amplifier 874, the PWM controller 520, the gate driver530, the oscillator 540, the functional block 880 for current bias, thefunctional block 882 for voltage bias, and/or the current and voltagegenerator 544 are reduced in comparison with the current consumption inRegion III and/or Region IV. In one embodiment, if the monitoring signal551 indicates the conditions for Region II are satisfied, theunder-voltage lockout (UVLO) threshold is made smaller in magnitudethrough the functional block 870 in comparison with the under-voltagelockout (UVLO) threshold in Region III.

As discussed above, and further emphasized here, FIG. 5 is merely anexample, which should not unduly limit the scope of the claims. One ofordinary skill in the art would recognize many variations, alternatives,and modifications. For example, instead of outputting the feedbacksignal 598 (e.g., V_(FB)) from the collector of the phototransistor 586as part of the photo coupler 578, a feedback signal (e.g., V_(FB)) isoutputted from the emitter of a phototransistor as part of a photocoupler as shown in FIG. 8.

FIG. 8 is a simplified diagram showing a power converter with dynamicmanagement of chip current consumption for PWM control according toanother embodiment of the present invention. This diagram is merely anexample, which should not unduly limit the scope of the claims. One ofordinary skill in the art would recognize many variations, alternatives,and modifications. The converter 900 includes a chip 910 for PWMcontrol, the power switch 120, the primary winding 130, the secondarywinding 132, the auxiliary winding 134, the diodes 140 and 144, thecapacitors 150, 152 and 154, the resistors 164 and 166, and an isolatedfeedback component 970.

The chip 910 for PWM control includes a PWM controller component 920, agate driver 930, an oscillator 940, a protection component 942, acurrent and voltage generator 944, a leading-edge-blanking component946, an over-current comparator 948, a management monitoring component950, a management control component 952, and an adjustable resistor 954.Also, the chip 910 for PWM control includes terminals 912, 914, 916,918, and 919. Additionally, the PWM controller component 920 includes aPWM comparator 922 and a logic controller 924. Moreover, the isolatedfeedback component 970 includes resistors 972, 973 and 974, a capacitor975, an error amplifier 976, and a photo coupler 978 that includes aphotodiode 984 and a phototransistor 986.

For example, the PWM controller component 920, the gate driver 930, theoscillator 940, the protection component 942, the current and voltagegenerator 944, the leading-edge-blanking component 946, and theover-current comparator 948 are the same as the PWM controller component520, the gate driver 530, the oscillator 540, the protection component542, the current and voltage generator 544, the leading-edge-blankingcomponent 546, and the over-current comparator 548, respectively.

As shown in FIG. 8, the chip 910 for PWM control is powered by at leastthe auxiliary winding 134 and the capacitor 150 through the terminal 916(e.g., V_(DD)) according to one embodiment. For example, the capacitor150 is used to provide a chip supply voltage 996 (e.g., V_(DD)) to thechip 910 through the terminal 916. In another example, the outputvoltage 999 (e.g., V_(o)) of the secondary winding 132 is sensed by theisolated feedback component 970, which generates a feedback signal 998(e.g., V_(FB)) that is received by the adjustable resistor 954. In yetanother example, both the PWM comparator 922 and the managementmonitoring component 950 also receive the feedback signal 998 throughthe terminal 918. In yet another example, the PWM comparator 922 alsoreceives a current sensing signal 994 and generates a PWM comparatoroutput signal 923. In yet another example, the PWM comparator outputsignal 923 is received by the logic controller 924, which generates thePWM signal 932 based on at least information associated with the PWMcomparator output signal 923. In yet another example, a feedbackimpedance associated with the terminal 918 (e.g., FB) changes withoutput load conditions.

In one embodiment, the feedback signal 998 (e.g., V_(FB)), the currentsensing signal 994 (e.g., V_(cs)), and the chip supply voltage 996(e.g., V_(DD)) are received by the management monitoring component 950.For example, the management monitoring component 950 compares thefeedback signal 998 (e.g., V_(FB)) with a feedback threshold (e.g.,V_(FB) _(—) _(th)), the current sensing signal 994 (e.g., V_(cs) thatrepresents a peak magnitude of a current 993 flowing through the primarywinding 130) with a current sensing threshold (e.g., V_(cs) _(—) _(th)),and the chip supply voltage 996 (e.g., V_(DD)) with both the supplyupper threshold (e.g., _(V) _(DD) _(—) _(th) _(—) _(h)) and the supplyupper threshold (e.g., V_(DD) _(—) _(th) _(—) _(h)). In another example,the management monitoring component 950 generates a monitoring signal951, which is received by the management control component 952. In yetanother example, the management control component 952 in response sendsa management control signal 953 to the adjustable resistor 954, theoscillator 940, the protection component 942, and the current andvoltage generator 944. In yet another example, the management controlsignal 953 includes one or more logic control signals.

In another embodiment, if the management monitoring component 950determines that the feedback signal 998 (e.g., V_(FB)) is larger thanthe feedback threshold (e.g., V_(FB) _(—) _(th)), the current sensingsignal 994 (e.g., V_(cs) that represents the peak magnitude of thecurrent 122) is smaller than the current sensing threshold (e.g., V_(cs)_(—) _(th)), and the chip supply voltage 996 (e.g., V_(DD)) is lowerthan the supply lower threshold (e.g., V_(DD) _(—) _(th) _(—) _(l)), themanagement monitoring component 950 sends the monitoring signal 951 tothe management control component 952 and in response the converter 900operates in Region II. For example, the management control component 952generates the management control signal 953, which is received by thegate driver 930, the adjustable resistor 954, the oscillator 940, theprotection component 942, and the current and voltage generator 944. Inanother example, in Region II, certain functional blocks in the chip910, e.g., a functional block for over-voltage protection, a functionalblock for over-temperature protection, a functional block forover-current protection, and/or a functional block for over-powerprotection, are powered down to reduce current consumption of the chip910.

In yet another embodiment, in Region II, the adjustable resistor 954become larger than in Region III and in Region IV. For example, theadjustable resistor 954 is biased between a ground voltage level throughthe terminal 919 (e.g., terminal GND) and the feedback signal 998 (e.g.,V_(FB)), so increasing the resistance value of the resistor 954 reducesthe current consumption of the chip 910. In another example, the changein resistance of the resistor 954 does not affect the loop gainstability even under no load condition. In yet another example, inRegion II, the under-voltage lockout (UVLO) threshold is made smaller inmagnitude in comparison with the under-voltage lockout (UVLO) thresholdin Region III.

According to another embodiment, if the management monitoring component950 determines that the feedback signal 998 (e.g., V_(FB)) is largerthan the feedback threshold (e.g., V_(FB) _(—) _(th)), the currentsensing signal 594 (e.g., V_(cs) that represents the peak magnitude ofthe current 993) is smaller than the current sensing threshold (e.g.,V_(cs) _(—) _(th)), and the chip supply voltage 596 (e.g., V_(DD)) ishigher than the supply upper threshold (e.g., V_(DD) _(—) _(th) _(—)_(h)), the management monitoring component 950 sends the monitoringsignal 951 to the management control component 952 and in response theconverter 900 operates in Region I. For example, the management controlcomponent 952 generates the management control signal 953, which isreceived by the gate driver 930, the adjustable resistor 954, theoscillator 940, the protection component 942, and the current andvoltage generator 944. In another example, in Region I, the currentconsumption of the chip 910 is larger than in Region II. In yet anotherexample, an extra current path is provided to discharge the capacitor150 in order to prevent the chip supply voltage 596 (e.g., V_(DD)) fromdrifting even higher. In yet another example, the converter 900 operatesin Region II when the management control signal 953 is at a logic lowlevel (or at a logic high level), and the converter 900 operates inRegion IV when the management control signal 953 is at the logic highlevel (or at the logic low level). In yet another example, themanagement control signal 953 includes two or more logic controlsignals, and the converter 900 operates in different Regions (e.g., asshown in FIG. 6) based on the status of the two or more logic controlsignals.

FIG. 9 is a simplified diagram showing a power converter with dynamicmanagement of chip current consumption for PWM control according to yetanother embodiment of the present invention. This diagram is merely anexample, which should not unduly limit the scope of the claims. One ofordinary skill in the art would recognize many variations, alternatives,and modifications.

The converter 1000 includes a chip 1010 for PWM control, the powerswitch 120, the primary winding 130, the secondary winding 132, theauxiliary winding 134, the diodes 140 and 144, the capacitors 150, 152and 154, the resistors 164 and 166, and an isolated feedback component1070. The chip 1010 for PWM control includes a PWM controller component1020, a gate driver 1030, an oscillator 1040, a protection component1042, a current and voltage generator 1044, a leading-edge-blankingcomponent 1046, an over-current comparator 1048, a management monitoringcomponent 1050, a management control component 1052, resistors 1061 and1063, and a transistor 1065. Also, the chip 1010 for PWM controlincludes terminals 1012, 1014, 1016, and 1018. For example, the PWMcontroller component 1020 includes a PWM comparator 1022 and a logiccontroller 1024. In another example, the isolated feedback component1070 includes resistors 1072, 1073 and 1074, a capacitor 1075, an erroramplifier 1076, and a photo coupler 1078 that includes a photodiode 1084and a phototransistor 1086.

In one embodiment, the PWM controller component 1020, the gate driver1030, the oscillator 1040, the protection component 1042, the currentand voltage generator 1044, the leading-edge-blanking component 1046,the over-current comparator 1048, and the isolated feedback component1070 are the same as the PWM controller component 520, the gate driver530, the oscillator 540, the protection component 542, the current andvoltage generator 544, the leading-edge-blanking component 546, theover-current comparator 548, and the isolated feedback component 570respectively. For example, the converter 1000 provides an output voltage1099 (e.g., V_(o)) and an output current (e.g., I_(o)) to the outputload 168, such as the output resistor.

As shown in FIG. 9, the PWM controller component 1020 generates a PWMsignal 1032, which is received by the gate driver 1030 according to oneembodiment. For example, the gate driver 1030, in response, sends a gatesignal 1092 to the power switch 120 through the terminal 1012 (e.g.,terminal Gate). In another example, in response, the power switch 120adjusts a current 1093 flowing through the primary winding 130. In yetanother example, the current 1093 is sensed by the resistor 166 andconverted into a current sensing signal 1094 (e.g., V_(cs)) through theterminal 1014 (e.g., terminal CS) and the leading-edge-blankingcomponent 1046. In yet another example, the current sensing signal 1094is received by the OCP comparator 1048 and compared with an over-currentthreshold signal 1095 (e.g., V_(th) _(oc)). In response, the OCPcomparator 1048 sends an over-current control signal 1049 to the logiccontroller 1024 according to certain embodiments.

According to another embodiment, the chip 1010 for PWM control ispowered by at least the auxiliary winding 134 and the capacitor 150through the terminal 1016 (e.g., terminal V_(DD)). For example, thecapacitor 150 is used to provide a chip supply voltage 1096 (e.g.,V_(DD)) to the chip 1010 through the terminal 1016. In another example,the output voltage 1099 (e.g., V_(o)) of the secondary winding 132 issensed by the isolated feedback component 1070. In yet another example,the isolated feedback component 1070 outputs a feedback signal 1098(e.g., V_(FB)) to the chip 1010 through the terminal 1018 (e.g.,terminal FB). In yet another example, the PWM comparator 1022 receivesthe feedback signal 1098 and the current sensing signal 1094, andgenerates a PWM comparator output signal 1023. In yet another example,the PWM comparator output signal 1023 is received by the logiccontroller 1024, which generates the PWM signal 1032 based on at leastinformation associated with the PWM comparator output signal 1023. Inyet another example, a feedback impedance associated with the terminal1018 (e.g., FB) changes with output load conditions.

As shown in FIG. 9, the resistor 1061 receives a reference signal 1055(e.g., V_(ref)) at one terminal and the other terminal of the resistor1061 is connected to the source terminal 1095 of the transistor 1065according to certain embodiments. For example, the transistor 1065 is aP-channel field effect transistor. In another example, the transistor1065 receives a reference signal 1057 (e.g., V_(ref2)) at a gateterminal 1066 and the feedback signal 1098 at a drain terminal 1068. Inyet another example, a source terminal 1095 of the transistor 1065 isconnected to one terminal of the resistor 1063, and the drain terminal1068 is connected to the other terminal of the resistor 1063. In yetanother example, the reference signal 1055 (e.g., V_(ref)) is largerthan the reference signal 1057 (e.g., V_(ref2)) in magnitude.

According to yet another embodiment, under light load or no loadconditions, the feedback signal 1098 has a low magnitude and in turn avoltage 1067 of the source terminal 1095 has a low magnitude. Forexample, if the voltage 1067 of the source terminal 1095 is lower thanthe reference signal 1057 in magnitude, an on-resistance of thetransistor 1065 is large, and there is no current or a limited amount ofcurrent flowing through the transistor 1065. Thus, an impedance at theterminal 1018 is approximately equal to a sum of the resistance of theresistor 1061 and the resistor 1063 according to certain embodiments.For example, a feedback current 1097 that flows out of the terminal 1018can be determined according to the following equation:

$\begin{matrix}{I_{FB} = \frac{V_{ref} - V_{FB}}{R_{1} + R_{2}}} & \left( {{Equation}\mspace{14mu} 2} \right)\end{matrix}$

where I_(FB) represents the feedback current 1097, V_(ref) represents areference signal 1055 received at the resistor 1061, and V_(FB)represents the feedback signal 1098. Additionally, R₁ represents theresistance of the resistor 1061, and R₂ represents the resistance of theresistor 1063. As an example, the feedback current 1097 decreases as theresistance of the resistor 1063 decreases. As another example, thefeedback current 1097 has a low magnitude under light load or no loadconditions. In yet another example, if the converter 1000 enters a burstmode under light load or no load conditions, the current consumption ofthe chip 1010 is greatly reduced during a burst-off period (e.g., whenthe feedback signal 1098 is less than the particular threshold inmagnitude). Hence the power consumption of the chip 1010 in the burstmode is greatly reduced according to certain embodiments.

In one embodiment, if the output load changes from the light load or noload to a full load, the feedback signal 1098 increases in magnitude andin turn the voltage 1067 of the source terminal 1095 increases inmagnitude. For example, if the voltage 1067 of the source terminal 1095is larger, in magnitude, than the reference signal 1057 plus a turn-onthreshold, the on-resistance of the transistor 1065 decreases and acurrent 1095 flows through the transistor 1065. In another example, theimpedance at the terminal 1018 can be determined according to thefollowing equation:

$\begin{matrix}{R_{FB} = {R_{1} + \frac{R_{2} \times R_{on}}{R_{2} + R_{on}}}} & \left( {{Equation}\mspace{14mu} 3} \right)\end{matrix}$

where R_(FB) represents the impedance at the terminal 1018, R₁represents the resistance of the resistor 1061, R₂ represents theresistance of the resistor 1063, and R_(on) represents the on-resistanceof the transistor 1065. In yet another example, the transistor 1065 hasa low on-resistance under the full-load condition, and the impedance atthe terminal 1018 is approximately equal to the resistance of theresistor 1061. The change in the impedance at the terminal 1018 underdifferent load conditions does not affect the loop stability accordingto some embodiments.

As shown in FIG. 9, the feedback signal 1098 (e.g., V_(FB)), the currentsensing signal 1094 (e.g., V_(cs)), and the chip supply voltage 1096 arereceived by the management monitoring component 1050 according tocertain embodiments. For example, the management monitoring component1050 compares the feedback signal 1098 with the feedback threshold(e.g., V_(FB) _(—) _(th)), the current sensing signal 1094 (e.g., V_(cs)that represents the peak magnitude of the current 1093) with the currentsensing threshold (e.g., V_(cs) _(—) _(th)), and the chip supply voltage1096 (e.g., V_(DD)) with both the supply upper threshold (e.g., V_(DD)_(—) _(th) _(—) _(h)) and the supply lower threshold (e.g., V_(DD) _(—)_(th) _(—) _(l)). In another example, the management monitoringcomponent 1050 generates a monitoring signal 1051, which is received bythe management control component 1052. In yet another example, themanagement control component 1052 in response sends a management controlsignal 1053 to the gate driver 1030, the oscillator 1040, the protectioncomponent 1042, and the current and voltage generator 1044. In yetanother example, the management control signal 1053 includes one or morelogic control signals.

According to another embodiment, if the management monitoring component1050 determines that the feedback signal 1098 (e.g., V_(FB)) is smallerthan the feedback threshold (e.g., V_(FB) _(v—) _(th)), the currentsensing signal 1094 (e.g., V_(cs) that represents the peak magnitude ofthe current 1093) is smaller than the current sensing threshold (e.g.,V_(cs) _(—) _(th)), and the chip supply voltage 1096 (e.g., V_(DD)) islower than the supply lower threshold (e.g., V_(DD) _(—) _(th) _(—)_(l)), the management monitoring component 1050 sends the monitoringsignal 1051 to the management control component 1052 and in response theconverter 1000 operates in Region II (e.g., as shown in FIG. 6). Forexample, the management control component 1052 generates the managementcontrol signal 1053, which is received by the gate driver 1030, theoscillator 1040, the protection component 1042, and the current andvoltage generator 1044 to adjust the power consumption or power downsome functional blocks. In another example, in Region II, the functionalblock for over-voltage protection, the functional block forover-temperature protection, the functional block for over-currentprotection, and/or the functional block for over-power protection arepowered down.

According to yet another embodiment, if the management monitoringcomponent 1050 determines that the feedback signal 1098 (e.g., V_(FB))is smaller than the feedback threshold (e.g., V_(FB) _(—) _(th)), thecurrent sensing signal 1094 (e.g., V_(cs) that represents the peakmagnitude of the current 1093) is smaller than the current sensingthreshold (e.g., V_(cs) _(—) _(th)), and the chip supply voltage 1096(e.g., V_(DD)) is higher than the supply upper threshold (e.g., V_(DD)_(—) _(th) _(—) _(h)), the management monitoring component 1050 sendsthe monitoring signal 1051 to the management control component 1052 andin response the converter 1000 operates in Region I (e.g., as shown inFIG. 6). For example, in Region I, the current consumption of the chip1010 is larger than in Region II. In yet another example, an extracurrent path is provided to discharge the capacitor 150 in order toprevent the chip supply voltage 1096 (e.g., V_(DD)) from drifting evenhigher. In yet another example, the converter 1000 operates in Region IIwhen the management control signal 1053 is at a logic low level (or at alogic high level), and the converter 1000 operates in Region IV when themanagement control signal 1053 is at the logic high level (or at thelogic low level). In yet another example, the management control signal1053 includes two or more logic control signals, and the converter 1000operates in different Regions (e.g., as shown in FIG. 6) based on thestates of the two or more logic control signals.

As discussed above, and further emphasized here, FIG. 9 is merely anexample, which should not unduly limit the scope of the claims. One ofordinary skill in the art would recognize many variations, alternatives,and modifications. For example, instead of outputting the feedbacksignal 1098 (e.g., V_(FB)) from the collector of the phototransistor1086 as part of the photo coupler 1078, a feedback signal (e.g., V_(FB))is outputted from the emitter of the phototransistor 1086. In anotherexample, instead of applying the reference signal 1057 on the gateterminal of the transistor 1065, a management control signal generatedfrom a management control component is applied on the gate terminal ofthe transistor as shown in FIG. 10.

FIG. 10 is a simplified diagram showing a power converter with dynamicmanagement of chip current consumption for PWM control according to yetanother embodiment of the present invention. This diagram is merely anexample, which should not unduly limit the scope of the claims. One ofordinary skill in the art would recognize many variations, alternatives,and modifications.

The converter 1100 includes a chip 1110 for PWM control, the powerswitch 120, the primary winding 130, the secondary winding 132, theauxiliary winding 134, the diodes 140 and 144, the capacitors 150, 152and 154, the resistors 164 and 166, and an isolated feedback component1170. The chip 1110 for PWM control includes a PWM controller component1120, a gate driver 1130, an oscillator 1140, a protection component1142, a current and voltage generator 1144, a leading-edge-blankingcomponent 1146, an over-current comparator 1148, a management monitoringcomponent 1150, a management control component 1152, resistors 1161 and1163, and a transistor 1165. Also, the chip 1110 for PWM controlincludes terminals 1112, 1114, 1116, and 1118. For example, the PWMcontroller component 1120 includes a PWM comparator 1122 and a logiccontroller 1124. In another example, the isolated feedback component1170 includes resistors 1172, 1173 and 1174, a capacitor 1175, an erroramplifier 1176, and a photo coupler 1178 that includes a photodiode 1184and a phototransistor 1186.

In one embodiment, the PWM controller component 1120, the gate driver1130, the oscillator 1140, the protection component 1142, the currentand voltage generator 1144, the leading-edge-blanking component 1146,the over-current comparator 1148, and the isolated feedback component1170 are the same as the PWM controller component 520, the gate driver530, the oscillator 540, the protection component 542, the current andvoltage generator 544, the leading-edge-blanking component 546, theover-current comparator 548, and the isolated feedback component 570respectively. For example, the converter 1100 provides an output voltage1199 (e.g., V_(o)) and an output current (e.g., I_(o)) to the outputload 168, such as the output resistor.

As shown in FIG. 10, the PWM controller component 1120 generates a PWMsignal 1132, which is received by the gate driver 1130 according to oneembodiment. For example, the gate driver 1130, in response, sends a gatesignal 1192 to the power switch 120 through the terminal 1112 (e.g.,terminal Gate). In another example, in response, the power switch 120adjusts a current 1193 flowing through the primary winding 130. In yetanother example, the current 1193 is sensed by the resistor 166 andconverted into a current sensing signal 1194 (e.g., V_(cs)) through theterminal 1114 (e.g., terminal CS) and the leading-edge-blankingcomponent 1146. In yet another example, the current sensing signal 1194is received by the OCP comparator 1148 and compared with an over-currentthreshold signal 1195 (e.g., V_(th) _(—) _(oc)). In response, the OCPcomparator 1148 sends an over-current control signal 1149 to the logiccontroller 1124 according to certain embodiments.

According to another embodiment, the chip 1110 for PWM control ispowered by at least the auxiliary winding 134 and the capacitor 150through the terminal 1116 (e.g., terminal V_(DD)). For example, thecapacitor 150 is used to provide a chip supply voltage 1196 (e.g.,V_(DD)) to the chip 1110 through the terminal 1116. In another example,the output voltage 1199 (e.g., V_(o)) of the secondary winding 132 issensed by the isolated feedback component 1170. In yet another example,the isolated feedback component 1170 outputs a feedback signal 1198(e.g., V_(FB)) to the chip 1110 through the terminal 1118 (e.g.,terminal FB). In yet another example, the PWM comparator 1122 receivesthe feedback signal 1198 and the current sensing signal 1194, andgenerates a PWM comparator output signal 1123. In yet another example,the PWM comparator output signal 1123 is received by the logiccontroller 1124, which generates the PWM signal 1132 based on at leastinformation associated with the PWM comparator output signal 1123. Inyet another example, a feedback impedance associated with the terminal1118 (e.g., FB) changes with output load conditions.

According to yet another embodiment, the feedback signal 1198 (e.g.,V_(FB)), the current sensing signal 1194 (e.g., V_(cs)), and the chipsupply voltage 1196 are received by the management monitoring component1150. For example, the management monitoring component 1150 compares thefeedback signal 1198 with the feedback threshold (e.g., V_(FB) _(—)_(th)), the current sensing signal 1194 (e.g., V_(cs) that representsthe peak magnitude of the current 1193) with the current sensingthreshold (e.g., V_(cs) _(—) _(th)), and the chip supply voltage 1196(e.g., V_(DD)) with both the supply upper threshold (e.g., V_(DD) _(—)_(th) _(—) _(h)) and the supply lower threshold (e.g., V_(DD) _(—) _(th)_(—) _(l)). In another example, the management monitoring component 1150generates a monitoring signal 1151, which is received by the managementcontrol component 1152. In yet another example, the management controlcomponent 1152 in response sends a management control signal 1153 to thegate driver 1130, the oscillator 1140, the protection component 1142,and the current and voltage generator 1144. In yet another example, themanagement control signal 1153 includes one or more logic controlsignals.

As shown in FIG. 10, the resistor 1161 receives a reference signal 1155(e.g., V_(ref)) at one terminal and the other terminal of the resistor1161 is connected to the source terminal 1195 of the transistor 1165according to certain embodiments. For example, the transistor 1165 is aP-channel field effect transistor. In another example, the transistor1165 receives the management control signal 1153 at a gate terminal 1166and the feedback signal 1198 at a drain terminal 1168. In yet anotherexample, a source terminal 1195 of the transistor 1165 is connected toone terminal of the resistor 1163, and the drain terminal 1168 isconnected to the other terminal of the resistor 1163.

In one embodiment, under light load or no load conditions, the feedbacksignal 1198 has a low magnitude and in turn a voltage 1167 of the sourceterminal 1195 has a low magnitude. For example, if the voltage 1167 islower than the management control signal 1153 in magnitude, anon-resistance of the transistor 1165 is large, and there is no currentor a limited amount of current flowing through the transistor 1165.Thus, an impedance at the terminal 1018 is approximately equal to a sumof the resistance of the resistor 1161 and the resistor 1163 accordingto certain embodiments. For example, a feedback current 1197 that flowsout of the terminal 1118 can be determined according to the followingequation:

$\begin{matrix}{I_{FB} = \frac{V_{ref} - V_{FB}}{R_{1} + R_{2}}} & \left( {{Equation}\mspace{14mu} 4} \right)\end{matrix}$

where I_(FB) represents the feedback current 1197, V_(ref) represents areference signal 1155 received at the resistor 1161, and V_(FB)represents the feedback signal 1198. Additionally, R₁ represents theresistance of the resistor 1161, and R₂ represents the resistance of theresistor 1163. In another example, the feedback current 1197 decreasesas the resistance of the resistor 1163 decreases. In yet anotherexample, the feedback current 1197 has a low magnitude under light loador no load conditions. In yet another example, if the converter 1100enters a burst mode under light load or no load conditions, the currentconsumption of the chip 1110 is greatly reduced during a burst-offperiod (e.g., when the feedback signal 1198 is less than the lowerthreshold in magnitude). Hence the power consumption of the chip 1110 inthe burst mode is greatly reduced according to certain embodiments.

In another embodiment, if the output load changes from the light load orno load to a full load, the feedback signal 1198 increases and in turnthe voltage 1167 of the source terminal 1195 increases. For example, ifthe voltage 1167 of the source terminal 1195 is larger, in magnitude,than the management control signal 1153 plus a turn-on threshold, theimpedance at the terminal 1118 can be determined according to thefollowing equation when the transistor 1165 is turned on:

$\begin{matrix}{R_{FB} = {R_{1} + \frac{R_{2} \times R_{on}}{R_{2} + R_{on}}}} & \left( {{Equation}\mspace{14mu} 5} \right)\end{matrix}$

where R_(FB) represents the impedance at the terminal 1118, R₁represents the resistance of the resistor 1161, R₂ represents theresistance of the resistor 1163, and R_(on) represents the on-resistanceof the transistor 1165. As an example, the transistor 1165 has a lowon-resistance under the full-load condition, and the impedance at theterminal 1118 is approximately equal to the resistance of the resistor1161. The change in the impedance at the terminal 1118 under differentload conditions does not affect the loop stability according to someembodiments.

In another embodiment, if the management monitoring component 1150determines that the feedback signal 1198 (e.g., V_(FB)) is smaller thana feedback threshold (e.g., V_(FB) _(—) _(th)), the current sensingsignal 1194 (e.g., V_(cs) that represents the peak magnitude of thecurrent 1193) is smaller than a current sensing threshold (e.g., V_(cs)_(—) _(th)), and the chip supply voltage 1196 (e.g., V_(DD)) is lowerthan a supply lower threshold (e.g., V_(DD) _(—) _(th) _(—) _(l)), themanagement monitoring component 1150 sends the monitoring signal 1151 tothe management control component 1152 and in response the converter 1100operates in Region II (e.g., as shown in FIG. 6). For example, themanagement control component 1152 generates the management controlsignal 1153, which is received by the gate driver 1130, the oscillator1140, the protection component 1142, and the current and voltagegenerator 1144 to adjust the power consumption or power down somefunctional blocks. In another example, in Region II, the functionalblock for over-voltage protection, the functional block forover-temperature protection, the functional block for over-currentprotection, and/or the functional block for over-power protection arepowered down.

In yet another embodiment, if the management monitoring component 1150determines that the feedback signal 1198 (e.g., V_(FB)) is smaller thanthe feedback threshold (e.g., V_(FB) _(—) _(th)), the current sensingsignal 1194 (e.g., V_(cs) that represents the peak magnitude of thecurrent 1193) is smaller than the current sensing threshold (e.g.,V_(cs) _(—) _(th)), and the chip supply voltage 1196 (e.g., V_(DD)) ishigher than the supply upper threshold (e.g., V_(DD) _(—) _(th) _(—)_(h)), the management monitoring component 1150 sends the monitoringsignal 1151 to the management control component 1152 and in response theconverter 1100 operates in Region I (e.g., as shown in FIG. 6). Forexample, in Region I, the current consumption of the chip 1110 is largerthan in Region II. In yet another example, an extra current path isprovided to discharge the capacitor 150 in order to prevent the chipsupply voltage 1196 (e.g., V_(DD)) from drifting even higher. In yetanother example, the converter 1100 operates in Region II when themanagement control signal 1153 is at a logic low level (or at a logichigh level), and the converter 1100 operates in Region IV when themanagement control signal 1153 is at the logic high level (or at thelogic low level). In yet another example, the management control signal1153 includes two or more logic control signals, and the converter 1100operates in different Regions (e.g., as shown in FIG. 6) based on thestates of the two or more logic control signals.

As discussed above, and further emphasized here, FIG. 10 is merely anexample, which should not unduly limit the scope of the claims. One ofordinary skill in the art would recognize many variations, alternatives,and modifications. For example, instead of connecting the transistor1165 in parallel with the resistor 1163 to adjust the impedance at theterminal 1118, the feedback impedance is adjusted using a differentscheme as shown in FIG. 11.

FIG. 11 is a simplified diagram showing a power converter with dynamicmanagement of chip current consumption for PWM control according to yetanother embodiment of the present invention. This diagram is merely anexample, which should not unduly limit the scope of the claims. One ofordinary skill in the art would recognize many variations, alternatives,and modifications.

The converter 1200 includes a chip 1210 for PWM control, the powerswitch 120, the primary winding 130, the secondary winding 132, theauxiliary winding 134, the diodes 140 and 144, the capacitors 150, 152and 154, the resistors 164 and 166, and an isolated feedback component1270. The chip 1210 for PWM control includes a PWM controller component1220, a gate driver 1230, an oscillator 1240, a protection component1242, a current and voltage generator 1244, a leading-edge-blankingcomponent 1246, an over-current comparator 1248, a management monitoringcomponent 1250, a management control component 1252, resistors 1261 and1263, and a transistor 1265. Also, the chip 1210 for PWM controlincludes terminals 1212, 1214, 1216, and 1218. For example, the PWMcontroller component 1220 includes a PWM comparator 1222 and a logiccontroller 1224. In another example, the isolated feedback component1270 includes resistors 1272, 1273 and 1274, a capacitor 1275, an erroramplifier 1276, and a photo coupler 1278 that includes a photodiode 1284and a phototransistor 1286.

In one embodiment, the PWM controller component 1220, the gate driver1230, the oscillator 1240, the protection component 1242, the currentand voltage generator 1244, the leading-edge-blanking component 1246,the over-current comparator 1248, and the isolated feedback component1270 are the same as the PWM controller component 520, the gate driver530, the oscillator 540, the protection component 542, the current andvoltage generator 544, the leading-edge-blanking component 546, and theover-current comparator 548, and the isolated feedback component 570respectively. For example, the converter 1200 provides an output voltage1299 (e.g., V_(o)) and an output current (e.g., I_(o)) to the outputload 168, such as the output resistor.

As shown in FIG. 11, the PWM controller component 1220 generates a PWMsignal 1232, which is received by the gate driver 1230 according to oneembodiment. For example, the gate driver 1230, in response, sends a gatesignal 1292 to the power switch 120 through the terminal 1212 (e.g.,terminal Gate). In another example, in response, the power switch 120adjusts a current 1293 flowing through the primary winding 130. In yetanother example, the current 1293 is sensed by the resistor 166 andconverted into a current sensing signal 1294 (e.g., V_(cs)) through theterminal 1214 (e.g., terminal CS) and the leading-edge-blankingcomponent 1246. In yet another example, the current sensing signal 1294is received by the OCP comparator 1248 and compared with an over-currentthreshold signal 1295 (e.g., V_(th) _(—) _(oc)). In response, the OCPcomparator 1248 sends an over-current control signal 1249 to the logiccontroller 1224 according to certain embodiments.

According to another embodiment, the chip 1210 for PWM control ispowered by at least the auxiliary winding 134 and the capacitor 150through the terminal 1216 (e.g., terminal V_(DD)). For example, thecapacitor 150 is used to provide a chip supply voltage 1296 (e.g.,V_(DD)) to the chip 1210 through the terminal 1216. In another example,the output voltage 1299 (e.g., V_(o)) of the secondary winding 132 issensed by the isolated feedback component 1270. In yet another example,the isolated feedback component 1270 outputs a feedback signal 1298(e.g., V_(FB)) to the chip 1210 through the terminal 1218 (e.g.,terminal FB). In yet another example, the PWM comparator 1222 receivesthe feedback signal 1298 and the current sensing signal 1294, andgenerates a PWM comparator output signal 1223. In yet another example,the PWM comparator output signal 1223 is received by the logiccontroller 1224, which generates the PWM signal 1232 based on at leastinformation associated with the PWM comparator output signal 1223. Inyet another example, a feedback impedance associated with the terminal1218 (e.g., FB) changes with output load conditions.

According to yet another embodiment, the feedback signal 1298 (e.g.,V_(FB)), the current sensing signal 1294 (e.g., V_(cs)), and the chipsupply voltage 1296 are received by the management monitoring component1250. For example, the management monitoring component 1250 compares thefeedback signal 1298 with the feedback threshold (e.g., V_(FB) _(—)_(th)), the current sensing signal 1294 (e.g., V_(cs) that representsthe peak magnitude of the current 1293) with the current sensingthreshold (e.g., V_(cs) _(—) _(th)), and the chip supply voltage 1296(e.g., V_(DD)) with both the supply upper threshold (e.g., V_(DD) _(—)_(th) _(—) _(h)) and the supply lower threshold (e.g., V_(DD) _(—) _(th)_(—) _(l)). In another example, the management monitoring component 1250generates a monitoring signal 1251, which is received by the managementcontrol component 1252. In yet another example, the management controlcomponent 1252 in response sends a management control signal 1253 to thegate driver 1230, the oscillator 1240, the protection component 1242,and the current and voltage generator 1244. In yet another example, themanagement control signal 1253 includes one or more logic controlsignals.

As shown in FIG. 11, the transistor 1265 (e.g., a P-channel field effecttransistor) receives a reference signal 1255 (e.g., V_(ref)) at a sourceterminal 1269 and the management control signal 1253 at a gate terminal1266 according to certain embodiments. For example, one terminal of theresistor 1261 is connected to the source terminal 1269 of the transistor1265, and the other terminal of the resistor 1261 is connected to thedrain terminal 1268 of the transistor 1265. In another example, thedrain terminal 1268 is connected to the resistor 1263. In yet anotherexample, the resistor 1263 receives the feedback signal 1298.

In one embodiment, under light load or no load conditions, the feedbacksignal 1298 has a low magnitude and in turn a voltage 1267 of the drainterminal 1268 has a low magnitude. For example, if the managementcontrol signal 1253 is larger than the reference signal 1255 (e.g.,V_(ref)) in magnitude, an on-resistance of the transistor 1265 is large,and there is no current or a limited amount of current flowing throughthe transistor 1265. Thus, an impedance at the terminal 1218 isapproximately equal to a sum of the resistance of the resistor 1261 andthe resistor 1263 according to certain embodiments. For example, afeedback current 1297 that flows out of the terminal 1218 can bedetermined according to the following equation:

$\begin{matrix}{I_{FB} = \frac{V_{ref} - V_{FB}}{R_{1} + R_{2}}} & \left( {{Equation}\mspace{14mu} 6} \right)\end{matrix}$

where I_(FB) represents the feedback current 1297, V_(ref) represents areference signal 1255 received at the resistor 1261, and V_(FB)represents the feedback signal 1298. Additionally, R₁ represents theresistance of the resistor 1261, and R₂ represents the resistance of theresistor 1263. In another example, the feedback current 1297 decreasesas the resistance of the resistor 1263 decreases. In yet anotherexample, the feedback current 1297 has a low magnitude under light loador no load conditions. In yet another example, if the converter 1200enters a burst mode under light load or no load conditions, the currentconsumption of the chip 1210 is greatly reduced during a burst-offperiod (e.g., when the feedback signal 1298 is less than the lowerthreshold in magnitude). Hence the power consumption of the chip 1210 inthe burst mode is greatly reduced according to certain embodiments.

In another embodiment, if the output load changes from the light load orno load to a full load, the feedback signal 1298 increases and in turnthe voltage 1267 of the drain terminal 1268 increases. For example, ifthe reference signal 1255 (e.g., V_(ref)) is larger, in magnitude, thanthe management control signal 1253 plus a turn-on threshold, theimpedance at the terminal 1218 can be determined according to thefollowing equation when the transistor 1265 is turned on:

$\begin{matrix}{R_{FB} = {R_{1} + \frac{R_{2} \times R_{on}}{R_{2} + R_{on}}}} & \left( {{Equation}\mspace{14mu} 7} \right)\end{matrix}$

where R_(FB) represents the impedance at the terminal 1218, R₁represents the resistance of the resistor 1261, R₂ represents theresistance of the resistor 1263, and R_(on) represents the on-resistanceof the transistor 1265. As an example, the transistor 1265 has a lowon-resistance under the full-load condition, and the impedance at theterminal 1218 is approximately equal to the resistance of the resistor1263. The change in the impedance at the terminal 1218 under differentload conditions does not affect the loop stability according to someembodiments.

In another embodiment, if the management monitoring component 1250determines that the feedback signal 1298 (e.g., V_(FB)) is smaller thana feedback threshold (e.g., V_(FB) _(—) _(th)), the current sensingsignal 1294 (e.g., V_(cs) that represents the peak magnitude of thecurrent 1293) is smaller than a current sensing threshold (e.g., V_(cs)_(—) _(th)), and the chip supply voltage 1296 (e.g., V_(DD)) is lowerthan a supply lower threshold (e.g., V_(DD) _(—) _(th) _(—) _(l)), themanagement monitoring component 1250 sends the monitoring signal 1251 tothe management control component 1252 and in response the converter 1200operates in Region II (e.g., as shown in FIG. 6). For example, themanagement control component 1252 generates the management controlsignal 1253, which is received by the gate driver 1230, the oscillator1240, the protection component 1242, and the current and voltagegenerator 1244 to adjust the power consumption or power down somefunctional blocks. In another example, in Region II, the functionalblock for over-voltage protection, the functional block forover-temperature protection, the functional block for over-currentprotection, and/or the functional block for over-power protection arepowered down.

In yet another embodiment, if the management monitoring component 1250determines that the feedback signal 1298 (e.g., V_(FB)) is smaller thanthe feedback threshold (e.g., V_(FB) _(—) _(th)), the current sensingsignal 1294 (e.g., V_(cs) that represents the peak magnitude of thecurrent 1293) is smaller than the current sensing threshold (e.g.,V_(cs) _(—) _(th)), and the chip supply voltage 1296 (e.g., V_(DD)) ishigher than the supply upper threshold (e.g., V_(DD) _(—) _(th) _(—)_(h)), the management monitoring component 1250 sends the monitoringsignal 1251 to the management control component 1252 and in response theconverter 1200 operates in Region I (e.g., as shown in FIG. 6). Forexample, in Region I, the current consumption of the chip 1210 is largerthan in Region II. In yet another example, an extra current path isprovided to discharge the capacitor 150 in order to prevent the chipsupply voltage 1296 (e.g., V_(DD)) from drifting even higher. In yetanother example, the converter 1200 operates in Region II when themanagement control signal 1253 is at a logic low level (or at a logichigh level), and the converter 1200 operates in Region IV when themanagement control signal 1253 is at the logic high level (or at thelogic low level). In yet another example, the management control signal1253 includes two or more logic control signals, and the converter 1200operates in different Regions (e.g., as shown in FIG. 6) based on thestates of the two or more logic control signals.

According to another embodiment, a system controller for regulating apower conversion system includes a signal generator configured toreceive a feedback signal related to an output signal of a powerconversion system, a current sensing signal and an input voltage, and togenerate a control signal based on at least information associated withthe feedback signal, the current sensing signal and the input voltage,the current sensing signal representing one or more peak magnitudesrelated to a primary current flowing through a primary winding of thepower conversion system, and one or more power-consumption componentsconfigured to receive the control signal. The one or morepower-consumption components are further configured to reduce powerconsumption if the control signal indicates the feedback signal issmaller than a feedback threshold for a first predetermined period oftime, the current sensing signal is smaller than a current sensingthreshold for a second predetermined period of time, and the inputvoltage is smaller than a first threshold for a third predeterminedperiod of time in magnitude. Each of the first predetermined period oftime, the second predetermined period of time, and the thirdpredetermined period of time is equal to or larger than zero inmagnitude. For example, the system is implemented according to at leastFIG. 5, FIG. 6, FIG. 7, FIG. 8, FIG. 9, FIG. 10, and/or FIG. 11.

According to another embodiment, a system controller for regulating apower conversion system includes a signal generator configured toreceive a feedback signal related to an output signal of a powerconversion system, a current sensing signal and an input voltage, and togenerate a control signal based on at least information associated withthe feedback signal, the current sensing signal and the input voltage,the current sensing signal representing one or more peak magnitudesrelated to a primary current flowing through a primary winding of thepower conversion system, and one or more power-consumption componentsconfigured to receive the control signal. The one or morepower-consumption components are further configured to reduce powerconsumption if the control signal indicates the feedback signal islarger than a feedback threshold for a first predetermined period oftime, the current sensing signal is smaller than a current sensingthreshold for a second predetermined period of time, and the inputvoltage is smaller than a first threshold for a third predeterminedperiod of time in magnitude. Each of the first predetermined period oftime, the second predetermined period of time, and the thirdpredetermined period of time is equal to or larger than zero inmagnitude. For example, the system is implemented according to at leastFIG. 5, FIG. 6, FIG. 7, FIG. 8, FIG. 9, FIG. 10, and/or FIG. 11.

According to yet another embodiment, a system controller for regulatinga power conversion system includes a first resistor including a firstresistor terminal and a second resistor terminal, the first resistorterminal being biased to a first predetermined voltage, a secondresistor including a third resistor terminal and a fourth resistorterminal, the third resistor terminal being connected to the secondresistor terminal, the fourth resistor terminal configured to receive afeedback signal related to an output signal of a power conversionsystem, a transistor including a first transistor terminal, a secondtransistor terminal, and a third transistor terminal, the firsttransistor terminal being connected to the second resistor terminal andthe third resistor terminal, the second transistor terminal beingconfigured to receive a second predetermined voltage, the thirdtransistor terminal being configured to receive the feedback signal, amodulation component configured to receive the feedback signal andgenerate a modulation signal, and a gate driver configured to receivethe modulation signal and output a drive signal to a switch foradjusting a primary current flowing through a primary winding of thepower conversion system. For example, the system is implementedaccording to at least FIG. 9.

According to yet another embodiment, a method for regulating a powerconversion system includes receiving a feedback signal related to anoutput signal of a power conversion system, a current sensing signal andan input voltage, the current sensing signal representing one or morepeak magnitudes related to a primary current flowing through a primarywinding of the power conversion system, processing informationassociated with the feedback signal, the current sensing signal and theinput voltage, and generating a control signal based on at leastinformation associated with the feedback signal, the current sensingsignal and the input voltage. The method further includes receiving thecontrol signal, processing information associated with the controlsignal, and, if the control signal indicates the feedback signal issmaller than a feedback threshold for a first predetermined period oftime, the current sensing signal is smaller than a current sensingthreshold for a second predetermined period of time, and the inputvoltage is smaller than a first threshold for a third predeterminedperiod of time in magnitude, reducing power consumption of one or morepower consumption components. Each of the first predetermined period oftime, the second predetermined period of time, and the thirdpredetermined period of time is equal to or larger than zero inmagnitude. For example, the method is implemented according to at leastFIG. 5, FIG. 6, FIG. 7, FIG. 8, FIG. 9, FIG. 10, and/or FIG. 11.

For example, some or all components of various embodiments of thepresent invention each are, individually and/or in combination with atleast another component, implemented using one or more softwarecomponents, one or more hardware components, and/or one or morecombinations of software and hardware components. In another example,some or all components of various embodiments of the present inventioneach are, individually and/or in combination with at least anothercomponent, implemented in one or more circuits, such as one or moreanalog circuits and/or one or more digital circuits. In yet anotherexample, various embodiments and/or examples of the present inventioncan be combined.

Although specific embodiments of the present invention have beendescribed, it will be understood by those of skill in the art that thereare other embodiments that are equivalent to the described embodiments.Accordingly, it is to be understood that the invention is not to belimited by the specific illustrated embodiments, but only by the scopeof the appended claims.

1.-21. (canceled)
 22. A system controller for regulating a power conversion system, the system controller comprising: a signal generator configured to receive a feedback signal related to an output signal of a power conversion system, a current sensing signal and an input voltage, and to generate a control signal based on at least information associated with the feedback signal, the current sensing signal and the input voltage, the current sensing signal representing one or more peak magnitudes related to a primary current flowing through a primary winding of the power conversion system; and one or more power-consumption components configured to receive the control signal; wherein: the one or more power-consumption components are further configured to reduce power consumption if the control signal indicates the feedback signal is larger than a feedback threshold for a first predetermined period of time, the current sensing signal is smaller than a current sensing threshold for a second predetermined period of time, and the input voltage is smaller than a first threshold for a third predetermined period of time in magnitude; and each of the first predetermined period of time, the second predetermined period of time, and the third predetermined period of time is equal to or larger than zero in magnitude.
 23. The system controller of claim 22 wherein each of the first predetermined period of time, the second predetermined period of time, and the third predetermined period of time is larger than zero in magnitude.
 24. The system controller of claim 22 wherein the signal generator is further configured to determine whether the feedback signal is larger than the feedback threshold for the first predetermined period of time, the current sensing signal is smaller than the current sensing threshold for the second predetermined period of time, and the input voltage is smaller than the first threshold for the third predetermined period of time in magnitude.
 25. The system controller of claim 22, and further comprising: a feedback terminal configured to pass the feedback signal to the signal generator; wherein: an impedance associated with the feedback terminal changes with an output load of the power conversion system.
 26. A system controller for regulating a power conversion system, the system controller comprising: a first resistor including a first resistor terminal and a second resistor terminal, the first resistor terminal being biased to a first predetermined voltage; a second resistor including a third resistor terminal and a fourth resistor terminal, the third resistor terminal being connected to the second resistor terminal, the fourth resistor terminal configured to receive a feedback signal related to an output signal of a power conversion system; a transistor including a first transistor terminal, a second transistor terminal, and a third transistor terminal, the first transistor terminal being connected to the second resistor terminal and the third resistor terminal, the second transistor terminal being configured to receive a second predetermined voltage, the third transistor terminal being configured to receive the feedback signal; a modulation component configured to receive the feedback signal and generate a modulation signal; and a gate driver configured to receive the modulation signal and output a drive signal to a switch for adjusting a primary current flowing through a primary winding of the power conversion system.
 27. The system controller of claim 26, and further comprising: a signal generator configured to receive the feedback signal, a current sensing signal and an input voltage, and to generate a control signal based on at least information associated with the feedback signal, the current sensing signal and the input voltage, the current sensing signal representing one or more peak magnitudes related to a primary current flowing through a primary winding of the power conversion system; and one or more power-consumption components configured to receive the control signal; wherein: the signal generator is further configured to determine whether the feedback signal is larger than a feedback threshold for a first predetermined period of time, the current sensing signal is smaller than a current sensing threshold for a second predetermined period of time, and the input voltage is smaller than a first threshold for a third predetermined period of time in magnitude; the one or more power-consumption components are further configured to reduce power consumption if the control signal indicates the feedback signal is larger than the feedback threshold for the first predetermined period of time, the current sensing signal is smaller than the current sensing threshold for the second predetermined period of time, and the input voltage is smaller than the first threshold for the third predetermined period of time in magnitude; and each of the first predetermined period of time, the second predetermined period of time, and the third predetermined period of time is equal to or larger than zero in magnitude.
 28. The system controller of claim 27 wherein each of the first predetermined period of time, the second predetermined period of time, and the third predetermined period of time is larger than zero in magnitude.
 29. The system controller of claim 27 wherein the transistor includes a P-channel field effect transistor.
 30. The system controller of claim 29 wherein the first transistor terminal includes a source terminal, the second transistor terminal includes a gate terminal, and the third transistor terminal includes a drain terminal.
 31. The system controller of claim 30 wherein the first predetermined voltage is larger than the second predetermined voltage in magnitude.
 32. The system controller of claim 27 wherein the modulation component includes: a comparator configured to receive the feedback signal and the current sensing signal and generate a comparison signal based on at least information associated with the feedback signal and the current sensing signal; and a logic controller configured to receive the comparison signal and output the modulation signal based on at least information associated with the comparison signal.
 33. The system controller of claim 27, and further comprising: a feedback terminal configured to pass the feedback signal to the signal generator; wherein: an impedance associated with the feedback terminal changes with an output load of the power conversion system.
 34. A method for regulating a power conversion system, the method comprising: receiving a feedback signal related to an output signal of a power conversion system, a current sensing signal and an input voltage, the current sensing signal representing one or more peak magnitudes related to a primary current flowing through a primary winding of the power conversion system; processing information associated with the feedback signal, the current sensing signal and the input voltage; generating a control signal based on at least information associated with the feedback signal, the current sensing signal and the input voltage; receiving the control signal; processing information associated with the control signal; and if the control signal indicates the feedback signal is smaller than a feedback threshold for a first predetermined period of time, the current sensing signal is smaller than a current sensing threshold for a second predetermined period of time, and the input voltage is smaller than a first threshold for a third predetermined period of time in magnitude, reducing power consumption of one or more power consumption components; wherein: each of the first predetermined period of time, the second predetermined period of time, and the third predetermined period of time is equal to or larger than zero in magnitude.
 35. The method of claim 31 wherein each of the first predetermined period of time, the second predetermined period of time, and the third predetermined period of time is larger than zero in magnitude. 